Framed glasslike: Don't use cuboids to draw glass faces (#7828)

Framed glasslike: Don't use cuboids to draw glass faces (#7828)

Previously, each glass face used drawAutoLightedCuboid() to draw a
flat cuboid. This also disallowed backface culling, making the
backface culling inconsistent with 'glasslike'.

Use code from 'glasslike' to draw glass faces using drawQuad().

Remove long-unknown top/bottom textures feature:
Makes the code simpler and cleaner.
Never documented, long-unknown and not of much use.